mongodb - 如何从带有 mongo_dart 的集合中的数组中仅返回一个对象
问题描述
我目前在下面有这个集合，我需要一种方法来从内部数组中只返回一个项目（来自“pontosGastronomicos”数组的一个项目），只有对象，我对 mongodb 没有太多经验。我正在开发一个应用程序和 AngularDart 以及 Angel 中的后端，应用程序已经在工作，我只需要一种优化的方式来做到这一点。
// 1
{
"_id": ObjectId("6025b13eab1951094272d007"),
"id": "03a091e2-fa67-4132-9237-f5b9ed3dbb39",
"dataCadastro": "2021-02-11 19:35:41.998",
"link": null,
"icon": "icon-pizza-1",
"ativo": true,
"order": NumberInt("0"),
...
"pontosGastronomicos": [
{
"id": "208a3f93-9fcb-4db7-ac44-bb11b86a2d31",
"infos": [
{
"id": "925ed160-9276-4046-87a2-d1f37547f7cb",
"title": "BAR DA BOCA",
"lang": "pt",
"content": "Ótima experiência com o melhor chope de Rio das Ostras"
},
{
"id": "abc2ef60-4807-4b16-8d3e-95223abe0524",
"title": "BAR DA BOCA",
"lang": "en",
"content": "Great experience with the best draft beer in Rio das Ostras"
}
],
"midias": [
{
"id": "d54435d2-2fe3-4ea1-aa04-0ccdfade4c9f",
"title": "experimente-praias-1",
"description": "experimente-praias-1.jpg",
"dataCadastro": "2021-02-10 14:23:23.224",
"fisicalFilename": "acd13d50-15af-45fd-98f9-0903d1bb3ea5.jpg",
"originalFilename": "experimente-praias-1.jpg",
"link": "http://localhost:4002/storage/turismo/midias/acd13d50-15af-45fd-98f9-0903d1bb3ea5.jpg",
"mimeType": "image/jpeg",
"tipo": null
}
],
"ativo": true,
"dataCadastro": "2021-02-11 19:51:26.702",
"order": NumberInt("0"),
"link": null,
"email": "bardaboca@yahoo.com.br",
"logradouro": "Rua Teresópolis",
"bairro": "Boca da Barra",
"numero": "69",
"telefone1": "2227641671 ",
"telefone2": "22998578550",
"horarioFuncionamento": "10h as 20h",
"latitude": null,
"longitude": null,
"categoria": null,
"logo": null,
"whatsapp": null,
"tipoDeCozinha": null,
"capacidade": null,
"site": null,
"facebook": null,
"youtube": null,
"instagram": null,
"observacao": null,
}
]
}
我需要提出一个请求，通过 id 给我带来一个“pontosGastronomicos”，我目前通过终端执行此操作：
db.pontosGastronomicos.find(
{"pontosGastronomicos.id": "208a3f93-9fcb-4db7-ac44-bb11b86a2d31"},
{_id: 0, pontosGastronomicos: {$elemMatch: {id: "208a3f93-9fcb-4db7-ac44-bb11b86a2d31"}}});
结果是这样的：
{
"pontosGastronomicos": [
{
"id": "208a3f93-9fcb-4db7-ac44-bb11b86a2d31",
"infos": [
{
"id": "925ed160-9276-4046-87a2-d1f37547f7cb",
"title": "BAR DA BOCA",
"lang": "pt",
"content": "Ótima experiência com o melhor chope de Rio das Ostras"
},
{
"id": "abc2ef60-4807-4b16-8d3e-95223abe0524",
"title": "BAR DA BOCA",
"lang": "en",
"content": "Great experience with the best draft beer in Rio das Ostras"
}
],
"midias": [
{
"id": "d54435d2-2fe3-4ea1-aa04-0ccdfade4c9f",
"title": "experimente-praias-1",
"description": "experimente-praias-1.jpg",
"dataCadastro": "2021-02-10 14:23:23.224",
"fisicalFilename": "acd13d50-15af-45fd-98f9-0903d1bb3ea5.jpg",
"originalFilename": "experimente-praias-1.jpg",
"link": "http://localhost:4002/storage/turismo/midias/acd13d50-15af-45fd-98f9-0903d1bb3ea5.jpg",
"mimeType": "image/jpeg",
"tipo": null
}
],
"ativo": true,
"dataCadastro": "2021-02-11 19:51:26.702",
"order": NumberInt("0"),
"link": null,
"email": "bardaboca@yahoo.com.br",
"logradouro": "Rua Teresópolis",
"bairro": "Boca da Barra",
"numero": "69",
"telefone1": "2227641671 ",
"telefone2": "22998578550",
"horarioFuncionamento": "10h as 20h",
"latitude": null,
"longitude": null,
"categoria": null,
"logo": null,
"whatsapp": null,
"tipoDeCozinha": null,
"capacidade": null,
"site": null,
"facebook": null,
"youtube": null,
"instagram": null,
"observacao": null,
}
]
}
如何从带有 mongo_dart 的集合中的数组中仅返回一个对象
我希望结果是这样的
{
"id": "208a3f93-9fcb-4db7-ac44-bb11b86a2d31",
"infos": [
{
"id": "925ed160-9276-4046-87a2-d1f37547f7cb",
"title": "BAR DA BOCA",
"lang": "pt",
"content": "Ótima experiência com o melhor chope de Rio das Ostras"
},
{
"id": "abc2ef60-4807-4b16-8d3e-95223abe0524",
"title": "BAR DA BOCA",
"lang": "en",
"content": "Great experience with the best draft beer in Rio das Ostras"
}
],
"midias": [
{
"id": "d54435d2-2fe3-4ea1-aa04-0ccdfade4c9f",
"title": "experimente-praias-1",
"description": "experimente-praias-1.jpg",
"dataCadastro": "2021-02-10 14:23:23.224",
"fisicalFilename": "acd13d50-15af-45fd-98f9-0903d1bb3ea5.jpg",
"originalFilename": "experimente-praias-1.jpg",
"link": "http://localhost:4002/storage/turismo/midias/acd13d50-15af-45fd-98f9-0903d1bb3ea5.jpg",
"mimeType": "image/jpeg",
"tipo": null
}
],
"ativo": true,
"dataCadastro": "2021-02-11 19:51:26.702",
"order": NumberInt("0"),
"link": null,
"email": "bardaboca@yahoo.com.br",
"logradouro": "Rua Teresópolis",
"bairro": "Boca da Barra",
"numero": "69",
"telefone1": "2227641671 ",
"telefone2": "22998578550",
"horarioFuncionamento": "10h as 20h",
"latitude": null,
"longitude": null,
"categoria": null,
"logo": null,
"whatsapp": null,
"tipoDeCozinha": null,
"capacidade": null,
"site": null,
"facebook": null,
"youtube": null,
"instagram": null,
"observacao": null,
}
解决方案
我在 github 上得到了答案，对于其他有此困难的人，请遵循答案：
final cursor = db.collection(collection).modernAggregateCursor([
{
r'$replaceRoot': {
'newRoot': {
r'$arrayElemAt': [
{
r'$filter': {
'input': r'$pontosGastronomicos',
'as': 'pontosGastronomicos',
'cond': {
/* resolve to a boolean value and determine if an element should be included in the output array. */
r'$eq': [r'$$pontosGastronomicos.id', '208a3f93-9fcb-4db7-ac44-bb11b86a2d31']
}
}
},
0 /* the element at the specified array index */
]
}
}
}
]);
result = await cursor.nextObject();
await cursor.close();
/*result = await db.collection(collection).modernFindOne(filter: {
'pontosGastronomicos': {
r'$elemMatch': {'id': '208a3f93-9fcb-4db7-ac44-bb11b86a2d31'}
}
}, projection: {
'_id': 0,
'pontosGastronomicos': {
r'$elemMatch': {'id': '208a3f93-9fcb-4db7-ac44-bb11b86a2d31'}
}
});*/
print(result);
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